When you are using LV focusing, isn't it just another use of Autofocus?
And when using autofocus, there is a possible problem of front or back focusing.
(which can be corrected with the microfocus adjustments +1, +2, -1 -2 etc. etc.)
So this extra variable of a possible auto-focus mismatch is introduced.
So an auto-focus error is possibly introduced.
I do not want to test the focus.
I want to focus manually, and I am testing the resolving power of the lens.
The sharpness of the lens at proper focus.
So manually focusing eliminates the variable of an auto-focus lens/camera microfocus mismatch error.
I do not use auto-focus when shooting anyway.
Again, I'm curious if anyone has had a resolution problem (not an auto-focus error) - a soft lens - corrected by Canon?
You keep saying you don't want to test focus, but you
need to have accurate focus to be able to test resolving power of the lens, otherwise the test is pretty useless. Non-LV AF is not a reliable method unless you have calibrated the lens/camera combo.
LV focusing has the huge benefit in that it uses data from the sensor, and doesn't require calibration. There is no focus mismatch or front/back focusing issues with LF focus. Contrast detection focus (ie. LV focus), while slow (on DSLRs), is more accurate than non-LV AF or VF MF. Non-LV AF doesn't use use data from the sensor, but a different method similar to film SLR cameras, I believe it's called phase detection. MF through VF is not a reliable method for numerous reasons, from mirror mis-alignment, etc., and you need to have very good eyes and a bright VF, and/or a focusing screen.
So, to recap: test proper focus with LV AF or LV MF, and see if the images are as soft as non-LV AF or VF MF. If they are, it's unlikely you will get benefit from calibrating the lens. If they are sharper, calibrating the lens/camera will probably improve performance. But note that pictures done with LV AF/MF on a sturdy tripod and timer/remote release will show the best the lens can do, so that'll give you an idea of how soft the lens really is.
Much more about this
here. There's also a brand new video advertised on LL front page addressing your questions.